Hello @pchase
Thank you for contacting the Canvas Community. We're sorry to hear you've been experiencing issues with student enrollments. Concluding a student is likely your best option if there is a chance of the student re-enrolling at a later time. If you fully delete their account, you need to restore it to bring back their old enrollments when they sign up for new courses. Their old courses can still remain hidden from them via course settings, SIS section dates, term dates, etc. Ideally, you only delete users that will not be coming back to the school. You may want to contact Canvas Support and speak with your school CSM to see which option is best to fit your needs.
Here is the Canvas guides:
https://community.canvaslms.com/t5/Admin-Guide/How-do-I-suspend-and-reactivate-users-in-an-account/t...
https://community.canvaslms.com/t5/Admin-Guide/How-do-I-conclude-a-course-at-the-end-of-a-term-as-an...
https://community.canvaslms.com/t5/Admin-Guide/How-do-I-delete-a-user-from-an-account/ta-p/136
You can also bulk inactivate students and conclude them from courses via csv SIS import:
https://canvas.instructure.com/doc/api/file.sis_csv.html
